The objective of the present investigation was to determine the aerodynamic characteristics of ejection seat occupants. 3D RANS equations are solved to calculate the aerodynamic coefficient. The commercially available CFD software ANSYS Fluent was used for analysis. An unstructured grid of polyhedral elements is generated for the ejection seat occupant using ANSYS meshing. For investigation, two different models with different positions of seat occupants were built. For validation purposes, the analysis of the sphere is performed at Mach number (Ma) = 0.2. Later on, the analysis was carried out for both models at Ma = 0.2. Finally, the analysis was carried out for different angles of attack (α) = − 15°, − 10°, − 5°, 0°, 5°, 10°, 15°. The two models’ pressure contours and aerodynamic characteristics were obtained. This analysis is helpful in understanding the aerodynamic characteristics of the ejection seat system at different positions and α at subsonic speed.

Shock wave and boundary layer interaction (SBLI) plays important role in design of supersonic inlet for various aerospace vehicles. Flow separation induced due to shock impingement can cause increase in drag and unstart conditions both of which degrade the efficiency and performance of the intake. To address the issue of shock-induced separation, Micro Vortex Generators (MVGs) are typically placed upstream of the shock interaction point. These devices create streamwise vortices that enhance boundary layer momentum thus helping in prevention of flow separation. In this study, effect of various shapes of MVGs on SBLI was analysed using computational fluid dynamics. Specifically, MVGs with curved sidewalls were used to investigate how localized flow modification impacts SBLI control. Study has indicated that the curvature of the side wall affects the formation of streamwise vortices. MVGs with inward curved wall exhibit higher pressure gradient, resulting in formation of stronger vortex due to vortex stretching.

Solid particle transportation via pipelines has been a standard procedure for several industries, like the oil and gas, food, and pharmaceutical sectors. Especially in coal mining and ocean mining industries, large particles are transported using water as a medium through vertical pipes. The literature on the simulation of vertical slurry pipelines is found to be few, and the particle size used is in microns. Power consumption and pressure losses have remained a challenging issue in vertical pipes. Understanding vertical slurry flows is necessary because they have bigger pressure drops and higher losses than horizontal slurry flows. This work presents numerical modelling of a two-phase slurry flow in the vertical pipeline using ANSYS Fluent 17.2 software. Eulerian–Eulerian Approach is used to analyse slurry flow in vertical upward flow. A 3D model of 3.8 m long with 54.9 mm-diameter pipe is used for this analysis. Particle size 1–2 mm with density 2200 kg/m3 and viscosity 0.000017 Pa-s is considered. Simulations are conducted at 2 m/s slurry velocity with a solid volume fraction of 10

The ejection seat system is a piece of crucial military aircraft equipment that saves a pilot's life in emergencies. Developments in the aerospace industries and new generations of fighter aircraft continuously demand improved ejection seat systems. An enormous number of studies were done to enhance the design concept of the ejection seat and reduce the aerodynamic instability of the pilot's body. The experimental and numerical analyses were performed to determine the effects of aerodynamic forces responsible for the pilot's injuries. Due to time limitations, cost-effectiveness, and experimental constraints, Computational Fluid Dynamics (CFD) analysis has been extensively performed in the past thirty years. A detailed review has been done on the experimental and computational approaches used for analyzing the aerodynamic coefficients of ejection seat systems using the available literature published till now. All the methods used by different researchers to study the aerodynamic coefficients of an ejection seat system have been discussed.

In the present numerical investigation we studied the effect of forewing and hindwing stroke amplitude (ϕo) on the aerodynamic performance of dragonfly (or damselfly) hovering flight. Three-dimensional numerical simulation was performed for two wings with a tandem arrangement flapping along an inclined stroke plane. Simulations were conducted for identical as well as non-identical stroke amplitudes of both wings, oscillating with three phase differences:γ= 0∘, 90∘and180∘. For identical stroke amplitudes, the higher stroke amplitude reduces the vertical force coefficients of both wings. Forγ= 0∘, forewing lift is significantly enhanced for higher stroke amplitudes due to leading edge vortex interaction. Forγ= 90∘and180∘, the wing-wing interaction is found to be detrimental to the vertical force coefficient of both wings. The presence of the forewing reduces hindwing lift for allγ, with maximum lift reduction observed forγ= 180∘. The maximum hovering efficiency for identical stroke amplitudes is obtained forϕo= 50∘whenγ= 0∘. For non-identical stroke amplitudes, the hindwing lift reduces with an increase in forewing stroke amplitude for allγ. Also, forewing lift increases with hindwing stroke amplitude whenγ= 0∘. However, forγ= 90∘and180∘, forewing lift is reduced for higher hindwing stroke amplitudes. It was found that non-identical stroke amplitudes are detrimental to the hovering efficiency of dragonfly flight. The present study will help us optimize wing kinematics during the development of dragonfly-inspired micro air vehicles.

The mixed compression scramjet engine intake was numerically simulated to study the characteristic of shock wave induced boundary layer separation leading to the formation of the separation bubble (SB). The analysis employed a 2D-RANS method with SST k-omega turbulence model at different Mach numbers. The intake is designed as a three-ramp intake for improved performance. As the Mach number varies, the size of the separation bubble formed due to the interaction of oblique shock waves with the boundary layer also varies, affecting both intake the efficiency and overall efficiency of the engine. Apart from traditional control techniques, the most preferred bleed technique is incorporated. Localised & distributed bleed techniques are designed and analysed within the intake at different locations. These techniques result in a reduction in the size of the separation bubble within the intake. Establishing perforation in the engine intake also increases the intake efficiency and overall engine performance.

In this study, the commercially available CFD software ANSYS-Fluent is used to conduct a three-dimensional unsteady-state analysis of the aerodynamic coefficients of an ejection seat system. The aerodynamic coefficients are calculated by solving Reynolds-averaged Navier–Stokes equations. ANSYS meshing software is utilized to create an unstructured grid of tetrahedral cells for this analysis. The validation of the numerical methodology is performed initially on a sphere at subsonic Mach number (Ma) for different Reynolds numbers (Re) before the validation of the ejection seat system. The computed unsteady-state results are compared with the experimental and available numerical results for both the sphere and the ejection seat. Later the aerodynamic coefficients of the ejection seat are further investigated at Ma = 0.7 by changing the angle of attack (α) and yaw angle (β). The findings of this study show that the magnitude of the axial force coefficient (CX) and values of the side force coefficient (CY), normal force coefficient (CZ), pitching moment coefficient (Cm), yawing moment coefficient (Cn), and rolling moment coefficient (Cl) changes with the variation of the α and β.

A 3D numerical analysis on an adiabatic flat plate for multi-hole trench cooling with forward, backward and mixed injection holes is performed in the current investigation. The numerical setup is validated before the performances of different cooling configurations are compared. The effect of three different multi-hole trench arrangements, square-diamond, long-diamond, and super-long-diamond with constant perforated percentage (3.27%), on film cooling performance is studied at blowing ratio 1.0. The row-to-row interaction between coolant jets and mainstream is analysed, and lateral film cooling effectiveness is calculated downstream. The dimensionless temperature contour overlaid with streamlines concluded that the SLD trench hole arrangement with forward injection forms a developed effusion layer due to counter-rotating vortex pairs, which helps in proper mixing of coolant jets into the mainstream and improves film cooling effectiveness in lateral as well as in longitudinal direction. It is observed that super-long-diamond arrangement with forward injection provides the highest film cooling effectiveness than square-diamond and long-diamond arrangements and favours early development of the coolant film layer.

In the last few years, due to the superior mechanical qualities of Additive Manufacturing (AM) AlSi10Mg alloy to those of traditional casting process AlSi10Mg alloys, the application of AM technology has significantly increased. The ballistic impact research has a wide range of uses, notably in the mining, construction, spacecraft and defence sectors. This work focuses on analyzing the behavior of different projectile nose shapes on the AlSi10Mg alloy fabricated by AM. There are several projectile nose forms to consider, including blunt, hemispherical, conical, and ogive shapes. The impact of various projectile shapes on the ballistic limit of the additively created AlSi10Mg alloy is carefully examined in this study. All numerical simulations were carried out using LS-DYNA software, and the Johnson-Cook material and damage model were considered to assess the ballistic resistance behavior. The ballistic limit for various projectile shapes is computed using the Jonas-Lambert model, which describes the connection between residual velocity and starting projectile velocity. The results showed that, the ogive-shaped Projectile offers the highest ballistic limit, and the blunt projectile shows the lowest ballistic limit for a 5 mm thin target plate. The ballistic impact phenomenon showed plugging failure for the blunt nose projectile, the formation of plug and small fragments were observed in the case of hemispherical nose projectile, fragmenting failure is observed with radial necking in the case of conical nose projectile and petals are formed at the impacted zone in ogive nose shape projectile. Moreover, the ballistic limit of AM AlSi10Mg alloy was slightly higher compared to the ballistic limit of the die-cast AlSi10Mg alloy for the 7.62 mm AP bullet (core). Therefore, AM AlSi10Mg alloy may have equal or good ballistic properties compared to die-cast AlSi10Mg alloy.

A 3D numerical analysis on an adiabatic flat plate for multi-zone trench cooling is performed in the current investigation. A super-long-diamond (SLD) arrangement with continuous (20 rows) and a three-zone 5×5×5 (15 rows) trench hole configuration is used with 30° forward coolant injection at blowing ratio (BR) 1.0. A velocity profile of 1/7 power law is set at the mainstream inlet for the present study. The SLD arrangement with a three-zone 5×5×5 trench hole configuration has been studied, and a comparison between continuous (20 rows) and a three-zone 5×5×5 (15 rows) trench hole configuration has been made. Results show that the super-long-diamond arrangement with a three-zone 5×5×5 (15 rows) trench holes provides almost similar cooling as continuous (20 rows), which reduces the number of effusion holes and the coolant mass requirement. The effectiveness of lateral film cooling is determined downstream after analysing the row-to-row interaction between coolant jets and mainstream. According to the dimensionless temperature contours overlaid with streamlines, a three-zone 5×5×5 (15 rows) trench hole configuration with forward injection produces a developed effusion layer due to counter-rotating vortex pairs, which helps in proper coolant jet mixing into the mainstream and boosts the effectiveness of film cooling in both the longitudinal and laterally directions.

A numerical investigation is carried out to study the role of inclined stroke plane on the aerodynamic performance of a dragonfly during a take-off flight. A two-dimensional numerical simulation of tandem foils oscillating in-phase along an inclined stroke plane at Re = 160 is performed using ANSYS Fluent. The stroke plane angle is varied from 10° ≤ β ≤ 80° to determine its effect on aerodynamic force coefficients of forefoil and hindfoil. The result shows that the presence of forefoil reduces the hindfoil Cv for low stroke plane angle cases. The cycle-average vertical force coefficient Cv of both foils increases with β up to 50° and then decreases. A vortex pair is present in the wake of the foils during each cycle, which induces a downward dipole jet. The dipole jet characteristics such as jet width, location and maximum velocity components are measured for each stroke plane angle. It is observed that the cause of variation in Cv and CH with stroke plane angle can be explained with the help of dipole jet characteristics.

A computational study of a three ramped dual duct Rocket Based Combined Cycle (RBCC) engine inlet at scramjet mode using different types of MVG (micro vortex generator) arrays were conducted. The definite geometry of engine inlet was operated at hypersonic speeds of Mach 5 and 7 to study the effect of the arrays of delta ramp (DR), rectangular vane (RRV) and ramp vane (RV) on the pressure recovery, exit Mach number, the mass flow rate and Shock wave Boundary Layer interaction (SWBLI). The study was performed considering same heights for all the configurations of MVG array and were positioned at the point of shock impingement on the ramp which caused the separation bubble. The computational analysis was done using k-omega model in Fluent Workbench of Ansys.

A numerical analysis has been conducted to study the role of hindfoil initial pitch angle on aerodynamic performance of dragonfly hovering flight. The inclined oscillation of two elliptic airfoils with tandem arrangment at Re=157 is analysed using 2D numerical simulation. The pitch amplitude ( α _m ) is kept constant for both foils and hindfoil initial pitch angle ( α _o_h ) is varied from 15^o to 75^o for three different phase oscillations: φ = 0^o , 90^o and 180^o . The results indicate, for α _o_h < 45^o , the lower α _o_h reduces total lift for all phase differences. It occurs due to the detrimental wake capture and downward dipole jet encountered by hindfoil during downstroke, resulting in less hindfoil -C_V . However, for α _o_h > 45^o , lift enhancement of up to 46 % is observed with increase in α _o_h during φ = 180^o . Also, the higher thrust is obtained during lower α _o_h and it reduces with increase in α _o_h .

In the present study, a 3-D analysis of the aerodynamic coefficients of the ejection seat system is performed using Computational Fluid Dynamics (CFD) software ANSYS-Fluent. For this investigation, an unstructured grid of polyhedral cells is created. The Reynolds Averaged Navier-Stokes (RANS) equations are solved with the standard k - epsilon turbulence model to calculate the aerodynamic coefficients. Before this analysis, a simple blunt bodylike sphere is analyzed to understand the physics and the boundary conditions suitable for external flow aerodynamics at subsonic speed.The drag coefficient (Cd) on the sphere is calculated and matched with the experimental results at Mach number (Ma) = 0.6, 0.46, and 0.33 . Later on, for validation purposes, the analysis of the ejection seat system is performed at Ma = 0.6. Finally, the aerodynamic coefficients are measured for angle of attack (a) = -75 degrees, -60 degrees, -45 degrees, -30 degrees, -15 degrees, 0 degrees, 150, 30 degrees, 45 degrees, 60 degrees, and 75 degrees at Ma = 0.7 and yaw angle (beta) = 0 degrees. It is observed that with the increase of a the magnitude of the axial force coefficient (Cx) is increasing up to a = -15 degrees and after that, it decreases with the increase of a. The normal force coefficient (Cz) is decreasing with the increase of a and at a = -75 degrees, the maximum value of the Cz is found. The minimum value of the pitching moment coefficient (Cm) is found at a = 00, whereas the value of the Cm increases as the a changes from 00.

In the present study, a 3-D study of the aerodynamic coefficients of an ejection seat system is performed. The analysis is performed using the Reynolds Averaged Navier-Stokes equations where an unstructured grid of the polyhedral cells is used. The aerodynamic coefficients are calculated using a density-based solver and the standard k-ε turbulence model. The investigation is performed at Mach number (Ma) = 1.25 by varying the angle of attack (α) from -15° to 15° with the increment of 5° where the yaw angle (β) is fixed at 0°. According to the findings, the magnitude of the axial force coefficient (CX) increases as α decreases whereas the value of the normal force coefficient (CZ) decreases with the increase of α. Similarly, the value of the pitching moment coefficient (Cm) decreases with the increase of α.

This research paper proposes a unique way to safeguard delicate systems on submerged platforms from the undesirable effects of underwater explosion shock loads. The underwater detonation of an explosive charge and mines produce devastating underwater shocks against underwater platforms. Shock load developed underwater has been analyzed, and a shock response spectrum (SRS) approach to compute shock peak responses has been adopted. SRS shock absorption frequency satisfies requirements for both shock absorption and delicate systems. The shock load was reduced to 2g by altering the delicate system stiffness and damping properties. The analytical model for a single DOF system was formulated, and simulation was carried out using ANSYS solver. The stiffness has been spread across various points along the length of the delicate system, allowing it to undergo translational oscillations when subjected to shock loads. This research paper presents an innovative design approach for a shock absorption system intended for underwater sensitive objects, emphasizing simplicity, distinctiveness, compactness, reliability, and electromagnetic compatibility. Experimental testing validated the shock absorption design on the prototype. Shock testing determined the absorber's maximum displacement and sensitive object acceleration.